Metacarpal bone mass (D2-d2)/D2 measured on radiographs, and bone mineral content (BMC) measured by photon absorptiometry, were studied in the forearms of 30 nondialyzed and 25 hemodialyzed patients with chronic failure and in a group of normal subjects. Metacarpal bone mass was reduced in nondialyzed women with chronic renal failure and the amount of bone mineral reduced both in males and females with chronic renal failure, whereas these measurements were normal in dialyzed patients with chronic renal failure. Bone mineral content in the forearm and metacarpal bone mass decreased with age, both in women with chronic renal failure and in normal women, the decrease being more pronounced in women with chronic renal failure than in normal women. No age-related decrease was seen in males. Bone mineral content corrected for the size of bone (BMC') decreased with age both in males and in females. Highly significant correlations were found between metacarpal bone mass and BMC' in nondialyzed and dialyzed patients with chronic renal failure, whereas no significant correlation could be demonstrated in normal subjects. The study indicates that changes in metacarpal bone mass and in BMC to some degree occur simultaneously in patients with chronic renal failure; an accelerated loss of bone mass and of bone mineral with age may be seen in women with chronic renal failure compared to normal women.